Nearly 40,000 NYPD cops and civilians responded to the Sept. 11 attacks at Ground Zero — a staggering figure Mayor Bloomberg released yesterday amid a firestorm of controversy over the health of the police force, The Post has learned.

The mayor gave the exact number — 39,921 — along with each member’s job title, age, race and gender to the Mount Sinai School of Medicine, which is treating first responders and recently indicated the toxic dust at Ground Zero has caused an uptick in cancer.

Philip Landrigan, who is leading the study, said he has found a 14 percent increase in cancer rates among rescue workers — particularly prostate, thyroid and certain blood cancers.

His findings have been submitted to a journal for review and ultimately will be taken into account when federal officials decide whether to include cancer among the illnesses covered under the Zadroga Act for ailing first responders.